The present invention relates to a decoding technology of performing multiple error correction for a Reed-Solomon code or an extended Reed-Solomon code.
Reed-Solomon codes have been used in digital broadcasting, digital magnetic recording and the like. In a digital cable television system in the United States, for example, an extended Reed-Solomon code is adopted.
According to a first conventional technique, when an extended Reed-Solomon code is decoded, input data that is a received word is subjected to an error correction processing, the error corrected data is subjected to a syndrome computation again to obtain corrected data syndromes, and when the input data is erroneously corrected, the input data before the error correction is output (see European Laid-Open Patent Publication No. 1280281).
According to a second conventional technique, when an extended Reed-Solomon code is decoded, syndromes are generated from a received word, the number of errors generated in the received word is estimated from these syndromes, an initial value and end conditions are for an Euclidean algorithm operation are changed and error correction is carried out according to the estimated number of errors (see U.S. Pat. No. 6,131,178).
However, according to the first conventional technique, not only an extended component but also an unextended component is erroneously corrected in some cases.
According to the second conventional technique, if the number of errors is erroneously estimated, it is necessary to perform the Euclidean algorithm operation and a Chien search twice or more. This disadvantageously causes another erroneous correction in some cases.